• 한국생산제조학회지
• /
• 제23권2호
• /
• pp.157-163
• /
• 2014

In this paper, a robust MRAC (model reference adaptive control) scheme is applied to control an electrohydraulic positioning system under various loads. The inverse dead-zone compensator in the control system cancels out the dead-zone response, and an integrator added to the controller provides good position-tracking ability. LQG/LTR (linear quadratic Gaussian control with loop transfer recovery) closed-loop model is used as the reference model for learning the MRAC system. LQG/LTR provides a systematic technique to design the linear controller that optimizes the objective function using some compromise between the control effort and the system performance in the frequency domain. Different external load tests are performed to investigate the effectiveness of the designed MRAC system in real time. The experimental results show that the tracking performance of the proposed system is highly accurate, which offers considerable robustness even with a large change in the load.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2012년도 춘계학술대회 논문집
• /
• pp.614-619
• /
• 2012

A LQG/LTR(Linear Quadratic Gaussian/Loop Transfer Recovery) controller with an integrator is designed to control the electro-hydraulic positioning system. Without considering the nonlinearity in the dead-zone, computer simulations are performed and show good performances and tracking abilities with the feedback controller based on the linear system model. However, the performance of the closed loop hydraulic positioning system shows big steady-state error in real system because of the dead-zone. In this paper, the feedback controller with a nonlinear compensator is introduced to overcome the dead-zone phenomenon in hydraulic systems. The inverse dead-zone as a nonlinear compensator is used to cancel out the dead-zone phenomenon. Experimental tests are performed to verify the performance of the controller.

• 패션비즈니스
• /
• 제2권4호
• /
• pp.93-101
• /
• 1998

Knit products which had been limited only to underwear, recently became popularized, fashionized and highly classified covering even outer garments such as sportswear like golfwear, woman's dress, and man' s suit. As fashion cycle is getting shorter and the more a nation advanced prefers knit to woven fabrics knit industry has a very bright prospect, particularly woman's knit which is sensitive to fashion can be said as a fashion product with high value added. This study is to grasp the physical properties of stitch which are fundamental to the development of knit products. For this purpose, 2/20s of 100% wool were woven by the author of this study to basic plain stitch, rib stitch, varied transfer stitch, and float stitch on a SEMASEIKI cross knitter 7G to test the physical properties, and the result was as follows; 1. As for the relation between knit stitch and rate of extension recovery, rate of extension recovery was higher in the course direction than in the wale direction of three stitches except transfer stitch; rib stitch showed the highest rate of extension recovery in the course direction while float stitch showed the highest rate of extension recovery in the wale direction. 2. As for the relation between knit stitch and bursting strength elastic rib stitch showed higher bursting strength to indicate elasticity is an important factor of bursting strength and float stitch showed higher bursting strength too to indicate that the floating yarn on the surface plays a role of support. 3. As for the relation between knit stitch and air permeability perforated transfer stitch showed the lowest air permeability to prove that the size of perforation affects on the air permeability a great deal. 4. As for the relation between knit stitch and warmth retaining rib stitch through two lined needle bar showed the highest degree. The reason the warmth of perforated transfer stitch didn't decrease much was because the perforation wasn't big enough and content of air increased from the unevenness of the perforated parts through stitch variation. Based upon this result, each stitch can be characteristically summarized as follows; plain stitch showed a stable condition of knit cloth in four kinds of physical property test. And rib stitch is proper to tighten the edge of sleeve or clothe making use of its excellent extension recovery and to make socks for the highest bursting strength and warmth retaining. In the case of transfer stitch, seasonable designs can be taken by controlling the size of loop. Considering the pleasantness, underwear should be made of stitches with good air permeability float stitch was revealed to have color and pattern effects and a great bursting strength. This study has limitations in the aspect that it dealed with a small part of various knit stitches and the items of physical property test were not enough. The author of this study hopes that further studies would make deeper understandings about knit stitch based on more varied stitches and physical property tests ultimately to contribute to the development of fashionable designs proper to maximize the usage, function and originality.

• 한국항공우주학회지
• /
• 제34권2호
• /
• pp.36-47
• /
• 2006

인공위성에서 자세획득을 위해 기동을 하거나 이상상태 발생으로 위성이 임무를 수행하지 못하여 결국에 위성을 잃어버리게 되는 Flat Spin 상태에서 자세를 복구하는 방안인 Dual Spin Turn의 원리에 대한 연구가 수행되었다. Dual Spin Turn 현상에서 중요한 모멘텀 전달 원리를 물리적으로 명확하게 설명하였다. 그리고 기존의 연구결과에서 많이 알려진 방법을 포함하여 일반적인 위성의 관성모멘트 조건과 모멘텀 휠의 회전 방향 등을 여러 가지로 변화시켜 보면서 타당성을 검증하였다. Dual Spin Turn 과정은 개루프 제어와 에너지 감쇄장치의 도입이라는 2단계 제어방법을 이용하여 여러 경우에 대해 시뮬레이션으로 분석해보았다. 또한 제어의 타당성을 입증하기 위해 2단계 제어 이후의 안정성에 대해 검증하였다. 그리고 Dual Spin Turn을 이용하여 Flat Spin Recovery를 수행하는 시나리오를 예제로 제시하였다.

• 대한전자공학회논문지SD
• /
• 제48권2호
• /
• pp.1-6
• /
• 2011

본 논문은 위상 변조를 이용한 직렬 인터페이스 입출력 회로를 설계 하였다. 설계된 직렬 입출력 인터페이스 회로는 수신부와 송신부로 구성되어 있다. 제안하는 위상변조 데이터 전송 방식은 상승 에지 위상은 고정시켜 클록 정보로 사용하고 하강에지 위상을 전송되는 데이터에 따라 변조하여 오프-칩 인터페이스에서도 적용 가능한 효율적인 데이터 전송 방식을 사용한다. 제안하는 회로는 16개의 하강 에지 위상을 사용하여 한 클록 주기마다 4비트씩 데이터를 전송함으로써 시스템에서 사용되는 클록 속도보다 4배 빠른 전송 속도를 갖는 저 전력 회로다. 본 논문에서는 0.13um CMOS 공정을 이용하여 설계 및 검증을 수행 하였고, 칩 면적 $2mm^2$ 하에서 1Gb/s 전송 속도와 12mW의 소비 전력을 갖는다.

• 대한기계학회논문집
• /
• 제17권5호
• /
• pp.1123-1131
• /
• 1993

본 논문에서는 비행체의 사이드슬립(sideslip)의 변화를 최소로 하면서 롤(roll) 및 요(yaw) 운동을 제어하는 것을 제어목표로 하여, 입출력 갯수가 같은 정방(square)시스템과 입출력 갯수가 다른 비정방(nonsquare)시스템에 대하여 LQG/LTR 및 비례 재어기를 각각 설계하여 그 성능을 비교분석한다.

• 식물조직배양학회지
• /
• 제24권4호
• /
• pp.225-231
• /
• 1997

For genetic engineering to be commercially viable, an efficient transformation system is needed to produce transgenic plane from diverse genotypes ("generalized protocol"). Development of such a system requires optimization of a number of components such as gene transfer agent, plant tissues competent for both regeneration and transformation, and control of transgene expression. Although several novel gene transfer methods have been developed for plane, a majority of stably transformed plane express the introduced genes at low levels. Moreover, silencing of selectable marker genes shortly after their incorporation into plant chromosomes may result in low recovery of transgenic tissues from selection. Matrix attachment regions (MARs) are DNA sequences that bind to the cell's proteinaceous nuclear matrix to form DNA loop domains. MARs have been shown to increase transgene expression in tobacco cells, and reduce position in mature transgenic plants. Flanking an antibiotic resistance transgene with MARs should therefore lead to improved rates of transformation in a diversity of species, and may permit recalcitrant species and genotypes to be successfully transformed. Literature review and recent data from my laboratory suggest that MARs can serve as a transformation booster in recalcitrant plant species.

• 전자공학회논문지S
• /
• 제36S권2호
• /
• pp.38-45
• /
• 1999

본 논문에서는, $H_{\infty}-LTR$ 설계의 새로운 접근방법을 제시한다. 제시된 방법은 제어입력의 크기 및 회복오차의 적절한 가중을 조절할 수 있는 설계도구를 제공한다. 1단계에서, 요구되는 성능사양에 만족하도록 루프를 정형하기 위하여 Kalman 필터를 설계하고, 설계된 Kalman 필터는 플랜트의 전달함수와 함께 목표전달함수(target transfor function)로 사용된다. 2단계에서는 목표전달함수로 회복을 위하여 감도함수를 가중함수로 상요한 준 최적 $H_{\infty}_LTR$을 설계한다. 시뮬레이션을 통하여 LQG/LTR, $H_{\infty}-LTR$ 방법의 경과를 비교함으로써 제시된 $H_{\}-LTR$의 우수성을 보인다.

• Journal of Electrical Engineering and Technology
• /
• 제13권5호
• /
• pp.1886-1900
• /
• 2018

This paper proposes a confronting feedback control structure and controllers for positive output elementary super lift Luo converters (POESLLCs) working in discontinuous conduction mode (DCM). The POESLLC offers the merits like high voltage transfer gain, good efficiency, and minimized coil current and capacitor voltage ripples. The POESLLC working in DCM holds the value of not having right half pole zero (RHPZ) in their control to output transfer function unlike continuous conduction mode (CCM). Also the DCM bestows superlative dynamic response, eliminates the reverse recovery troubles of diode and retains the stability. The proposed control structure involves two controllers respectively to control the voltage (outer) loop and the current (inner) loop to confront the time-varying ON/OFF characteristics of variable structured systems (VSSs) like POESLLC. This study involves two different combination of feedback controllers viz. the proportional integral controller (PIC) plus sliding mode controller (SMC) and the fuzzy logic controller (FLC) plus SMC. The state space averaging modeling of POESLLC in DCM is reviewed first, then design of PIC, FLC and SMC are detailed. The performance of developed controller combinations is studied at different working states of the POESLLC system by MATLAB-Simulink implementation. Further the experimental corroboration is done through implementation of the developed controllers in PIC 16F877A processor. The prototype uses IRF250 MOSFET, IR2110 driver and UF5408 diodes. The results reassured the proficiency of designed FLC plus SMC combination over its counterpart PIC plus SMC.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.19-24
• /
• 2003

A new method for designing critical control systems is proposed in this paper. The controller structure is chosen as a Davison type integral controller with an observer. The proposed method consists of two steps. First, the state feedback critical control system is designed using a quadratic performance index with tunable parameters. Second, the observer gain matrix is determined by the formal LTR procedure using a Riccati equation. Consequently, the search space can be reduced considerably compared with the conventional approach. Although the proposed method sacrifices a large freedom for the choice of controller structure provided by the principle of matching, the controller structure used in this paper is not excessively complex and can be used for most applications. An illustrative design example is presented.